Monitoring the oceans is a matter of primary importance, not only for ongoing research related to global warming, but also for other activities such as oceanographic studies, the fishing industry, and military operations. For many of them, a number of different parameters such as temperature, salinity, wind speed and direction, wave height, are regularly measured over time and at different locations around the globe. Among the means available to obtain these measurements, buoys that gather and send data are widely used in observation and monitoring programs.
Existing buoys currently used for weather monitoring, acoustic transmission, etc. either require mooring lines to stay on site, or are allowed to drift away. Furthermore, in all cases, they need to be deployed by ships, thus implying a significant cost due to deployment alone. Whenever needed, maintenance is also another task which can be quite costly.
In the ocean engineering community, self-deployment and re-deployment was already considered in the form of autonomous self-propelled platforms, usually small robotic ships equipped with a propellers and thrusters. However, these solutions typically need a lot of energy and their batteries have to be re-charged quite often, thus limiting their life expectancy.
Instead of using propellers, it was also considered to resort to older means of sea transportation, whereby the wind would play a crucial role, and a number of robotic sailboats were built. The problem, in this case, and for monitoring platform applications such as data buoys, is that the appendages of the boats, i.e. the sails and the rudder, can after some time and harsh conditions be damaged by the marine environment, resulting again in a relatively short life expectancy.
If one considers the rudder, steering a sailboat without the aid of a rudder is not a new concept. The sailboard and all multi-masted craft are capable of being steered by their sails alone. In cases where the rudders of multi-masted craft have been damaged, the skipper's only means of steerage has been by properly trimming the sails to alter the balance between the aerodynamic and hydrodynamic forces. Likewise, the sailboard alters the balance between the aerodynamic and hydrodynamic forces by pivoting a single sail forward or backward over the center of lateral resistance of the keel. The rudderless sailboat offers yet another choice for the sports minded sailor. While the sailboard also uses a rudderless method of sailing, it is somewhat difficult to master and requires physical stamina and a good sense of balance. By contrast, the rudderless sailboat is easy to master and requires little effort to operate. However, all these examples still contain external moving parts (the sails, the keel or the mast) and are therefore not suited to longstanding operations in a sometimes extreme environment.
Mark Neal (IEEE Journal Of Oceanic Engineering, April 2006,Vol. 31, No. 2, pages 462-469) discloses an autonomous sailing buoy (sailing robot) comprising a buoy body taking the form of a simple boat hull and made from a robust material, a keel is attached to the bottom of the sailboat, a rigid sail (rigid wing) having a position along the plane between the front and aft of the buoy body. Neal further discloses a navigation unit (wind indicator potentiometer) and processing unit (main controller), where the processing unit (main controller) used for receiving and processing data from said navigation unit (wind indicator potentiometer).
The prior art does not disclose a buoy based on a sail boat without a rudder, and with a moving mass system inside the buoy body, and wherein the processing unit is connected to the moving mass system and said navigation unit, whereby it controls the moving mass system to hold the buoy on a specific course.
It is an object of the present invention to provide a buoy to go on site by itself and stay there, thereby removing the deployment costs. In addition, it is an object to provide a buoy that can go on site without the need of any fuel and without any moving parts extending from the buoy body. This will increase the life expectancy of such an autonomous buoy, requiring very little maintenance.